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Oxalic Acid Trickle report

A few weeks ago I began experimenting with o/a trickle. The fist batch I tried seemed not to work on a couple of test hives. Mixed a new batch Saturday and treated ten hives. Went back this am and did a sugar shake test on one hives that had a mite count of 25+ and found two mites. I was impressed. The option was buying $200 worth of apistan to treat 45 hives. I followed Mike Gillmore's recipe (with one exception) which was as follows:

OA - 17.5 g.
Sugar - 300 g.
Water - 300 ml.

Mix your sugar and hot water to make a syrup.
Dissolve the OA crystals in a small amount of alcohol and blend with syrup.

I purchased oxalic acid at Ace hardware and a 60ml syringe at tractor supply.
My daughter had a chemistry scale. A digital scale that weighs grams could be purchased at walmart.
I weighted out the water, sugar and oa, placed 1/4 of the water in a widemouth mason jar. I then heated the water in a glass measuring cup in the microwave and dissolved the sugar in the hot water. I added the acid to the water in the mason jar and with the lid closed shook until completely dissolved. I then added the syrup to the jar and mixed thoroughly. This recipe made about a pint which was enough to treat ten hives.

Application: I filled the syringe and dripped five ml between frames with bees. The oxalic acid took care of the rest.

Notes:

1. I will need to do more mite counts to verify uniform results.

2. Not sure why first batch didn't work. I followed a recipe that used hfcs instead of sugar syrup. Maybe I didn't mix thoroughly enough.

3. It looks like this method will cost me about ten to fifteen cents per hive.

Re: Oxalic Acid Trickle report

The first hives had only a small amount of brood. The current hives are broodless. I believe the amount of oxalic total volume was the same. Either my syrup was more or less diluted than it should have been or I didn't mix it enough.

Re: Oxalic Acid Trickle report

Harry,
Good point. I forgot to mention that I use distilled water only.
My formula I believe is about 2.9%
For a 3.4% concentration you would use about 20.4 g. of OA crystals with the same amount of water and sugar.
I've always had excellent knock down results with the formula I use, but the higher concentration might be better. Never tried it but it sounds like it works.

Re: Oxalic Acid Trickle report

This thread caused me to go back and check my math. Looks like I need to make a correction in the calculation. I have not been including the weight of the OA in the total weight of all ingredients combined.

Re: Oxalic Acid Trickle report

A further update

Just wanted to offer an update after doing mite counts after treating 25 hives with oxalic acid trickle. Most of the hives had no brood or very little brood. Pre treatment mite counts via sugar shake test of 200 bees yielded mite counts between 5 and 30 mites. Post treatment I am finding counts in most hives of 0-2. I have a couple of hives that are showing counts of 7 and 9 per 200 bees. I'm not sure what is happening in the hives showing the higher counts after oa treatments.

Since August I have tried several treatments on my hives and here's what I am seeing.

Apistan on two hives: (no follow up count)
Coumaphos: 4 hives: worthless
Hopguard on 5 hives: worthless
60% formic acid fumigator with honeybhealthy on 20 hives in August with large populations and brood nest with mite loads of 10-30 per 200: major knockdown to 2-4 mites per 200 bees, lost three queens
Oxalic Acid trickle: Tried a formula on 4 nucs and was not effective, mixed again with the formula mentioned above but with 19 or 20 grams of oa on 20 hives with zero brood or less than a six inch patch of brood and mite loads of 5-30 mites per 200: 3/4 show 0-2 mites, other 1/4 had 7-9 mites.

I will have to find a way to knock down mite loads that the oa didn't knock out. I'll probably use apistan.

Conclusion: There are no silver bullets. Formic fumigator is effective but is rough on queens. Probably needs to be used in late may or early june when I rob to knock back the spring buildup of mites while leaving opportunity to requeen if there is queen loss. Oxalic is good to clean up bees for winter but sometimes you can't wait until they are broodless to get rid of mites. I probably should look at thymol for a september application and use oxalic acid trickle for late nov/dec. Formic and Oxalic Acid are only pennies per hive. If I have to purchase a thymol based product such as apiguard or apilife var will add an additional $2.00 per hive.

Re: A further update

Thymol (Apiguard) worked well for me in three out of four treated hives. There appeared to be a correlation between removal of the gel from the tray and effectiveness of treatment. The fourth hive still has loads of mites, so I will be trying a "cleanup" treatment with OA in a couple of weeks.